Why is that a rhetorical question? It's a perfectly valid question.
Furthermore, it's backed by an SD card, so it's not as if any OS you choose completely monopolizes the platform. You don't need to choose just one when dealing with it.
If your Raspberry Pi is your only computer, then yeah, maybe this isn't for you, it does clearly say beta release on the page.
The beauty of the Pi is the fact you can have a variety of SD cards with different OS/Configurations and easily swap between them and play with them.
It is a very cheap educational tool. I have 4 of them, and they also make great network storage tools. Add a HDD, the transmission software and you can easily download TV shows and stream them to you 1080p TV for example. £27 in the UK, absolute bargain.